67 



■brown chrysalis in a light cocoon buried in the soil. The eggs are laid at the begin- 

 ning of spring on the most diiferent plants and trees ; the caterpillar is therefore 

 omnivorous. During the cotton season the moth prefers to lay its eggs on the cotton 

 plant. The eggs are massed on the under surface of the leaves in spots containing 

 from 200 to 300, covered with down and grayish-yellow scales. 



About a week after being laid the eggs hatch, and in about three days the young 

 caterpillars seek the tenderest parts of the plants and bury themselves in the young 

 buds and pods, which they quit when about one-third developed to feed afterwards 

 exclusively on the leaves. The young caterpillars are of a pale green and slightly 

 hairy. They then grow grayish, the hair is no longer perceptible, and their length 

 attains about 4 centimeters and their breadth 5 millimeters. 



This development is accomplished in from sixteen to twenty days, when they 

 bury themselves in the earth, where they enter the chrysalis state, out of which in a 

 week come the moths. A fall in temperature retards and an increase of heat accel- 

 erates the duration of these phases. The adult caterpillars have the habit of bury- 

 ing themselves in the earth at the foot of the plant during the hottest hours of the 

 day. This insect is the principal ravager of the cotton plant, but it is when the 

 caterpillar is young that it does the greatest damage by destroying the buds and 

 the ovaries of the young capsules, and when one wishes to fight the worm it is of 

 the utmost importance to act at the moment the eggs are laid, or at least immediately 

 after they are hatched, because if the young caterpillars once get into the pods they 

 are sheltered from any substance which may be applied to destroy them. 



The destruction of the leaves of the cotton plant by the adult caterpillars is but 

 a slight damage compared with the destruction of the pods by the small caterpillars. 



Of all the remedies which I have tried that which produced the best and surest ef- 

 fect is the following: Make a mixture of 10 per cent, raw carbolic acid at 30°, of 10 

 per cent. ]iowdered ammonlacal alum (avoid ferruginous alum), and of 80 per cent, 

 of au inert product such as ordinary plaster. Spread this on by hand at the rate of 

 about 85 to 90 pounds per acre. 



Tliis preparation, when made with acid of the necessary degree of concentration, 

 kills the worms without injuring the plants; only it should be applied when the 

 dew has disappeared, otherwise the plant being stil! damp, the tender shoot might be 

 burned. The picking oft' of the leaves before the eggs are hatched has a good effect, 

 but taking away the caterpillars when the plant is already attacked is almost use- 

 less. 



11. THE GNAWING MOTH. 



(Earias insulana Boisd.) 



This little moth also passes the winter in the state of a red chrysalis in a cocoon 

 shaped like a boat, and having a nankeen or gray color and a silky tissue. This 

 cocoon is attached to the dry shoots or to the branches of the cotton plant. The moth 

 is about 12 millimeters long and has a breadth of about 20 millimeters with the wings 

 extended. I have observed that during the summer most of them have the upper 

 wings of a light green, whilst in autumn and spring they are pale yellow, often with 

 grayish brown or violet spots or lines. The lower wings are of a shining white. 

 These differences in color are not due to the difference in sex, because during my 

 observations I have often seen moths coupling, both of which were of the same green 

 color. 



The females lay their eggs in spring on the young capsules. The caterpillar has 

 sixteen feet and attained a length of 15 millimeters and a diameter of 5 millimeters. 

 Its color is olive-brown. It has a glistening black head, with a yellowish face and a 

 white stripe on the middle of the back, the under part of the body being of an ash- 

 gray color. The skin is covered with white and orange-colored spines, interspersed, 

 with fine and rather long hairs. 



